<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>3_数据类型</title>
</head>
<body>
    <script>
        //JS数据类型 = 原始类型 + 引用类型
        //原始类型：number, string, boolean, null, undefined未定义型
        var a = 1;
        var b = 3.14;
        console.log(a, typeof a, b, typeof b);
        var c = "你好";
        var d = '你们好';
        console.log(c, typeof c, d, typeof d);
        var e = true;
        var f = false;
        console.log(e, typeof e, f, typeof f);
        var g;
        console.log(g, typeof g);
    </script>
</body>
</html>